A Study of Context-Awareness: The Context Fusion Network, The Context Fabric Presented by Sangkeun Lee IDS Lab., Seoul National University Solar: Building a Context Fusion Network for Per vasive Computing (2004) Guanling Chen Design and Implementation of a Large-Scale Context Fusion Network Guanling Chen, Ming Li, and David Kotz Department of Computer Science, dartmouth College Hanover, USA Context Fabric: Infrastructure Support for Conte xt-Aware Systems (2001) Jason I. Hong An Architecture for Privacy-Sensitive Ubiquitous Computing(2004) Jason I. Hong James A. Landay University of California at Berkeley

Copyright  2008 by CEBT Part I. The Context Fusion Network  Context Fusion Network (CFN) An infrastructure model that allows context applications to select distributed data sources and compose them with customized data- fusion operators Providing re-usability (code-level, instance-level)  The authors designed and implemented Solar Discussed some applications built with Solar 2

Copyright  2008 by CEBT Introduction  Context is set of environmental states and interactions that either determines an application’s behavior or in which an application event occurs and is interesting to the user  In general, it is not acceptable for individual applications to main tain connections to sensors and to process the raw data from scr atch  On the other hand, it is not feasible to deploy a common context service that could meet every application’s needs either 3

Copyright  2008 by CEBT Context Fusion Network  Context Delivery Network (CDN): connects multiple sources and sinks Source: Data producer, generally sensor Sink: Data Consumer, generally application  Context Fusion Network (CFN): provides CDN functionalities Additionally manages application specific data fusion functions  Challeneges to provide CFN in a heterogeneous and volatile ubi- comp environment 1.CFN must be flexible 2.CFN must be scalable to handle a large number of sensors, devices, applications and users 3.CFN must support mobility at both physical and logical level 4.CFN should be self-managed with minimum user intervention 4

Copyright  2008 by CEBT Architecture Style – Solar’s context fusion model 5

Copyright  2008 by CEBT Service Platform 6 Client mobility Data dissemination (Distribution) Naming and discovery Dependency management Load balancing

Copyright  2008 by CEBT Application – Meeting Detection 7 Not very impressive

Copyright  2008 by CEBT Part II.The Context Fabric  Primarily concerned with privacy rather than with context sensing and processing (wow!)  provides an architecture for privacy-sensitive systems, as well as a set of privacy mechanisms that can be used by application developers  Privacy related applications 8

Copyright  2008 by CEBT Introduction  Privacy? The claim of individuals, groups or institutions to determine for themselves when, how, and to what extent information about them is communicated to others [Westin] Most often-cited criticism  Previous work on privacy has tended to focus on anonymity or on keeping information from hackers While anonymity and secrecy are important, these don’t cover the many situation where people want to share information So, the Confab’s focus is in empowering people with choice and informed consent, so that they can share the right information, with the right people and services, in the right situation 9

Copyright  2008 by CEBT System Requirements  The end-user needs for Confab were gathered through scenario-based interviews  The application developer needs for Confab were gathered by identifying privacy functions common in several networked as well as ubicomp applications 10

Copyright  2008 by CEBT Confab System Architecture  Scenario – Mobile Tour Guide Alice is visiting boston for the first time She already has a location-enabled device She searches online and finds Bob’s location-aware tour guide service Bob offeres three levels of service – City level Bob can tell her how long the lines are at major venues – Neighborhood level Bob can also tell her what interesting shops there are and nearby points of interest – Street level as well as real-time maps and a route as well as real-time maps and a route 11

Copyright  2008 by CEBT Confab’s Data Model 12

Copyright  2008 by CEBT Confab’s Programming Model 13

Copyright  2008 by CEBT Context Fusion Network & Context Fabric  Chen et al. have implemented the CFN model in the form of Solar a scalable peer-to-peer platform which instantiates the operator graphs at runtime However, Solar does not yet address heterogeneity, privacy, or monitoring and control of the system by users.  Confab provides an architecture for privacy-sensitive systems it does not address traditional distributed systems requirements such as mobility, scalability, component failures and deployment/configurations 14 Reference: Middleware for Distributed Context-Aware Systems